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NCERT Solutions Curiosity Chapter 3 Activity 3.7: Let us infer — Treatment of diseases

Book page 41 Updated on2026-09-05

Q1.
Study the infographic given in Fig. 3.5b. How do you think the antibiotic resistance has been developed in bacterial pathogens?
Answer

It develops through the four steps shown in Fig. 3.5b, and it begins with something we do: taking antibiotics when they are not required, or taking an incomplete dose.

  1. A few bacteria develop resistance to antibiotics. In any large population of bacteria a small number happen to be able to survive the medicine.
  2. When antibiotics kill the bacteria causing illness, they also kill the good bacteria that protect the body from infection. The space and food that those bacteria were using is now free.
  3. The antibiotic-resistant bacteria grow and take over. With their competitors removed, the few survivors multiply into the majority.
  4. Some bacteria transfer antibiotic resistance to other bacteria, causing more problems. Resistance now spreads sideways, to kinds of bacteria that were never treated at all.
Why it happens: the antibiotic does not make bacteria resistant. It removes every bacterium that is not resistant, and so leaves the field to those that are. An incomplete dose is the worst case of all — enough medicine to wipe out the sensitive bacteria, not enough to finish the tougher ones, which then multiply undisturbed.

Fig. 3.5a adds the routes by which these resistant bacteria then reach everyone else: from antibiotics given to animals into animal food products; from manure and animal faeces into crop fields and so into our digestive system through crop produce; and from patient to patient in hospitals through dirty surfaces and healthcare workers, and then out into the community when patients go home.

The result, as the chapter says, is that bacteria that were earlier killed by a given antibiotic survive and multiply despite treatment — which makes common infections harder to treat and increases the risk of complications, prolonged illness and even death.

Q2.
What precautions may be taken to reduce antibiotic resistance?
Answer

The chapter states the rule directly: use antibiotics wisely — only when prescribed by a doctor, in the correct dose, and for the right duration.

PrecautionWhy it works
Take an antibiotic only when a doctor prescribes itRemoves the commonest cause — taking antibiotics when they are not required
Complete the full course, even after feeling betterKills the tougher bacteria too, instead of leaving them to multiply
Take the correct dose for the right durationA part-dose selects for resistance rather than curing the infection
Never take an antibiotic for a cold, cough or fluThese are viral — the antibiotic cannot help, and only breeds resistance
Do not use someone else’s leftover medicine, and do not share your ownThe dose and the medicine were chosen for a different infection
Do not give antibiotic injections to cattle without veterinary advice (Fig. 3.5b)Resistant bacteria from animals reach us through food products and manure
Prevent infection in the first place — handwashing, clean water, masks, vaccinationAn infection that never happens needs no antibiotic at all
Keep hospital surfaces and hands cleanBlocks the spread of resistant bacteria from patient to patient

As the chapter puts it, avoiding unnecessary use helps prevent the rise of resistant bacteria and keeps antibiotics effective for future generations.

Did you know? Penicillin, the first antibiotic, was discovered in 1928 by Alexander Fleming, a bacteriologist in London, when he noticed that a mould on a discarded petri dish had stopped bacteria from growing. Antibiotics have saved millions of lives since — which is exactly why they are worth protecting.
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